loft conversion cost

Loft Conversion Cost: What is the True Price?

Are you thinking of getting a loft conversion? Good idea, not only will it provide you and your family with more space, but your home should also get a better price when you come to sell. According to the HomeOwners Association this could be as high as 20%. In other words, getting a loft conversion is a win-win as long as you get the renovation right from the start and choose loft conversion specialists to do it for you.

Like most areas of life, cutting costs or rushing in without doing proper research always results in a bad situation. So it’s important to take days to educate yourself on subjects such as:

  • which tradesmen you’ll need and what to ask them
  • how long it’ll take to finish your conversation
  • Loft Conversion costs and the type that’s right for you
  • if you need planning permission or not

In the rest of this article we’ll go through each of the above points individually but would advise that you follow up with your own research too.

How Much Does a Loft Conversion Cost?

A loft conversion usually costs between £25,000 – £45,000. You might end up paying up to £63,000 if you want a very large extension. The biggest factors that affect price are the size, location, and the number of dormers.

Here is a rough guide for cost of the most popular loft conversions.

Types of Loft Conversions to Consider

The type of loft conversion you choose will depend on many things. The most important thing is how much you want to spend. Then there’s the question of whether or not the space will work or not. For example you have to consider what type of roof you have and whether there’s enough room for what you want. Lastly, if you’re likely to get the planning permission if necessary.


This is the most common type of loft extension in the London today, the Dormer is a small flat roofed extension with a window. Usually there will be two of these on the one roof for the sake of symmetry. But side dormers and L-shaped Dormers (where an extension is added to the back of the Dormer) are feasible too. With the latter it could result in up to four additional new rooms. Cost for these ranges from £30,000-£58,000 for a standard Dormer and £40,000-£60,000 for an L-shaped Dormer.

Hip to Gable

This is where one of both of the end sloping sections of the roof are replaced with a gable wall. Cost for these ranges from £42.000-£65,000.


The velux is the least expensive option and involves installing one or two windows to the roof in order to introduce light. Cost for these ranges from £20,000-£40,000.


The most extensive option, a Mansard extension is where the whole side of the roof is replaced to form a straight wall and flat roof. It could result in extending both sides, resulting in another storey. This is a major renovation and would involve planning permission. Cost: £45,000-£75,000.

Tradesmen Needed


Builders are of course needed to construct those walls in the first place and find out what is structurally possible. You’ll also need insulation and sound proofing. Ask what type of insurance that they have and if they offer a warranty.


To decide what type of windows are best.


Because of awful British weather, heating is a must. This engineer should be decide on the best place to put a heater. Also, if you’re going for a big conversion, would it be ok to fit solar panels?


There’s no doubt you’ll need lighting, as well as wall sockets to plug into. You need to consider is this tradesman qualified and listed on the government’s Registered Competent Person Scheme? Can he give you the necessary test certificate once he’s finished to allow you to pass Building inspections?


If you’ve decided on a larger extensions such as Hip to Gable and Mansard then you’re going to need temporary roof support.


You may want an en-suite bathroom if you’re planning to make the conversion an extra bedroom.


You will most likely need new ceiling joists since there’s going to be a lot more traffic. You might also want to ask your joiner about bespoke storage solutions as this can really help to maximize space in the conversion.


To smoothen out the new walls that are built.


Unless you plan on doing a bit of DIY decor you’ll need a good painter.

Length of Time to Finish the Conversion

How long your conversion will take to finish complete depends, of course, on what type you plan on getting in the first place. A Mansard loft conversion is the largest and can take up to two months from start to finish. While a Dormer has a a timescale of from four to six weeks and a double Velux should take around a month.

Planning Permission Needed?

Whether or not you need your local authority go-ahead depends on the type of conversion and the status of your home (if it’s listed then you’ll definitely need to inform the planning department of any alterations that you plan to make).

If the loft conversion is higher than the original roof or going to affect the view for others (as what happens with the Mansard) then neighbours are informed and given 21 days to lodge an objection.

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